Silane-crosslinking adhesive and sealing compounds contain as binders alkoxysilane-terminated or acyloxysilane-terminated polymers. Polymer systems having reactive alkoxysilyl groups have long been known. In the presence of atmospheric humidity, these alkoxysilane-terminated polymers are capable of condensing with one another, splitting off the alkoxy groups, even at room temperature. Depending on the alkoxysilane group content and their structure, mainly long-chain polymer (thermoplastics), relatively wide-mesh three-dimensional networks (elastomers) and highly crosslinked systems (thermosetting plastics) are formed.
As a rule, the polymers have an organic basic structure, which has the alkoxysilane groups. The basic organic structure may be, for example, polyurethanes, polyesters, polyesters, polyols, poly(meth)acrylates, polyvinyl alcohols, etc.
DE 197 27 029 A1 discloses a single-component reactive system composition containing an alkoxysilane-terminated polyurethane, a curing catalyst and conventional additives, if necessary.
WO 99/48942 A1 describes alkoxysilane-terminated polyurethanes and corresponding preparations that contain polyurethane and may also contain solvents, catalysts, plasticizers, reactive diluents, fillers and the like, in addition to the alkoxysilated polyurethanes.
EP 333222 B1 claims a curable polymer composition comprising a silylated polymer based on alkyl (meth)acrylate, a silylated polymer based on oxyalkylene, a silicon-containing compound and a curing accelerator.
U.S. Pat. No. 3,971,751 discloses silyl-terminated polymers containing essentially polyoxyalkylene units in the backbone for use in the field of sealing and adhesive compounds.
U.S. Pat. No. 3,278,457 discloses the synthesis of high-molecular polyoxyalkylene polymers with a high molecular weight distribution by so-called double metal cyanide catalysis.
EP 0397036 describes the introduction of reactive silyl groups capable of crosslinking onto such polyoxyalkylene polymers, e.g. by the hydrosilylation method.
U.S. Pat. No. 5,364,955 describes, as another method of attaching reactive silyl groups capable of crosslinking to such polyoxyalkylene polymers, the reaction of isocyanate-terminated polymers consisting of a polyoxyalkylene basic structure with aminosilanes.
EP 1678254 A1 describes the reaction of a hydroxyl-terminated polyoxyalkylene polymer (polyether polyols) with isocyanatosilanes to attach reactive silyl groups to polyoxyalkylene basic structures.
EP 1678254 A1 discloses polymeric compositions of mixed oxyalkylene units including both mixtures of polymers constructed from various oxyalkylene units and polymers constructed from different oxyalkylene units.
EP 327017 B1 claims a curing composition comprising a silylated oxyalkylene polymer, a polymeric plasticizer having an average (number average) molar weight of 500 to 15,000 g/mol and liquid polybutadiene.
WO 2005/042605 discloses moisture-curing polyether urethanes, which have an alkoxysilane functional finish. The reactive silyl groups are attached to the polyoxyalkylene polymer, which will later have at least two reactive silyl groups, by reaction of the polyoxyalkylene polymers which contains groups reactive with isocyanate groups, with silanes containing isocyanate. This silyl group is attached to the polyoxyalkylene polymer, which later has one reactive silyl group, by reaction of an aminosilane with an isocyanate group. This method results in the composition containing polymers having urea groups. However, urea groups can have a negative effect on the viscoelastic and/or plastic properties of the cured compositions as well as the processability of the curable compositions.
With all moisture-curing polyurethanes or preparations (systems) containing such polyurethanes, in particular, however, with the systems containing silicon, it is usually a disadvantage that these systems become brittle after processing due to the curing operation and thereby lose a large portion of their elasticity and/or have lower tear propagation strength values. The loss of elasticity occurs frequently at low temperatures in particular; on cooling, the known systems often lose their resilience and flexibility. However, attempts to improve the elasticity and flexibility of the cured systems often lead to an exacerbation of other material properties, e.g. a higher tackiness of the surface, or the systems have such a high viscosity before processing that solvents must be used, e.g. to ensure processability. Likewise, a reduction in stability of these systems is often observed during storage. Exacerbation of important material properties or storage properties and also the use of solvents are not acceptable, either economically or ecologically.
The use of plasticizers in such a system often cannot significantly improve the viscoelastic properties.
For example, for use in sealing compounds and highly elastic adhesives, low-molecular plasticizers, e.g. phthalates must be incorporated into the compositions to achieve the required elasticity. Not only are these plasticizers often objectionable toxicologically but also adding low-molecular compounds usually results in exacerbation of viscoelastic properties of the preparations, e.g. an increased viscosity of the curable composition. Furthermore, addition of low-molecular plasticizers has also a negative effect on the restoring force of the cured compositions, i.e., the cured compounds have inadequate restoring force.
High-molecular plasticizers in some cases also have an extremely negative effect on the processability of the uncured compositions. In addition, the use of high-molecular plasticizers can have an unfavorable influence on the elastic properties and the restoring force of the cured composition.